In recent years, while an environment for using the internet or the like has been prepared, measurement systems including remote metering of electrical power have been developed. In the past, in order to measure electrical power, an integrating wattmeter that converts an amount of used electrical power into the number of revolutions of a disk and performs an integration operation has been used. Recently, an ammeter (CT), a voltmeter (PT), or a sensor detecting a rotation is newly added to the integrating wattmeter, and electrical power is measured by performing a multiplication calculation through an electronic circuit or a microprocessor.
However, the integrating wattmeter is complicated in a device structure and large in a device size. In addition, in the integrating wattmeter, since electrical power is mechanically output, there is a problem in that it is difficult to perform digital management. Furthermore, since consumed electrical power is converted into rotation of the disk, a loss occurs, and extra energy is likely to be consumed.
In this regard, it is desirable to develop a compact integrated wattmeter which is capable of measuring consumed electrical power as a quantity of electricity without change.
For example, an electrical power measurement device and a magnetic field sensor which are capable of measuring electrical power consumption as a quantity of electricity using a magneto-resistance effect of a magnetic thin film have been proposed as the compact integrated wattmeter (Non-Patent Literatures 1 and 2). The electrical power measurement device and the magnetic field sensor are configured to employ a magnetic thin film (configured on a substrate) arranged in parallel to a primary conductor through which an alternating current (AC) flows is used, to cause a primary voltage to be applied to both ends of a magnetic thin film via a resistor, and to extract an output from both ends of the magnetic thin film. In the electrical power measurement device and the like, a scheme of extracting electrical power IV from an amplitude value of a double frequency component is employed.
The electrical power measurement device and the like are configured to extract a signal component that is in proportion to electrical power based on the fact that linear characteristics can be obtained without a bias magnetic field using a planar hall effect (PHE) that is a phenomenon that in a ferromagnet including a magnetic thin film, an electrical resistance value of a magnetic substance varies depending on an angle formed by an electric current and magnetization (this electrical power measuring apparatus is referred to as a “planar hole type electrical power measurement device” or a “PHE type electrical power measurement device”).
The magnetic field sensor used herein is an element of converting a change in an external magnetic field into an electrical signal. The magnetic field sensor is configured such that a magnetic thin film such as a ferromagnetic thin film or a semiconductor thin film is patterned, and causes an electric current to flow to the pattern of the magnetic thin film and converts a change in an external magnetic field into an electrical signal as a change in a voltage.
However, in the PHE type electrical power measurement device, a voltage to be detected has to be output from the magnetic thin film in a direction orthogonal to a load current of the primary conductor. That is, the voltage has to be outputted from both ends of the magnetic thin film in a width direction. Thus, in the PHE type electrical power measurement device, the magnetic thin film needs to have a relatively large width, and it is difficult to use a magnetic thin film having a narrow width shape (which means a shape that is fine in a longitudinal direction such as a straight line shape, or a rectangular shape).
Further, the PHE type electrical power measurement device has a shape restriction that the magnetic thin film has to be configured with a bridge circuit configuration. This means that in the PHE type electrical power measurement device, it is difficult to install it on a special line such as a microstrip line or a coplanar line used in a high-frequency circuit.
In addition, a bolometer and a precise measurement device are used as an electrical power measurement device for a high frequency. However, the bolometer and the precise measurement device have a complicated large configuration and are very expensive and thus are hardly used for electrical power measurement and detection of each device or each facility.